mm: slab-allocate memory section nodemask for large systems

Nodemasks should not be allocated on the stack for large systems (when it
is larger than 256 bytes) since there is a threat of overflow.

This patch causes the unregister_mem_sect_under_nodes() nodemask to be
allocated on the stack for smaller systems and be allocated by slab for
larger systems.

GFP_KERNEL is used since remove_memory_block() can block.

Cc: Gary Hade <garyhade@us.ibm.com>
Cc: Badari Pulavarty <pbadari@us.ibm.com>
Cc: Alex Chiang <achiang@hp.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/base/node.c b/drivers/base/node.c
index 4141411..7012279 100644 (file)
--- a/drivers/base/node.c
+++ b/drivers/base/node.c
@@ -363,12 +363,16 @@ int register_mem_sect_under_node(struct memory_block *mem_blk, int nid)
 /* unregister memory section under all nodes that it spans */
 int unregister_mem_sect_under_nodes(struct memory_block *mem_blk)
 {
-       nodemask_t unlinked_nodes;
+       NODEMASK_ALLOC(nodemask_t, unlinked_nodes, GFP_KERNEL);
        unsigned long pfn, sect_start_pfn, sect_end_pfn;
 
-       if (!mem_blk)
+       if (!mem_blk) {
+               NODEMASK_FREE(unlinked_nodes);
                return -EFAULT;
-       nodes_clear(unlinked_nodes);
+       }
+       if (!unlinked_nodes)
+               return -ENOMEM;
+       nodes_clear(*unlinked_nodes);
        sect_start_pfn = section_nr_to_pfn(mem_blk->phys_index);
        sect_end_pfn = sect_start_pfn + PAGES_PER_SECTION - 1;
        for (pfn = sect_start_pfn; pfn <= sect_end_pfn; pfn++) {
@@ -379,13 +383,14 @@ int unregister_mem_sect_under_nodes(struct memory_block *mem_blk)
                        continue;
                if (!node_online(nid))
                        continue;
-               if (node_test_and_set(nid, unlinked_nodes))
+               if (node_test_and_set(nid, *unlinked_nodes))
                        continue;
                sysfs_remove_link(&node_devices[nid].sysdev.kobj,
                         kobject_name(&mem_blk->sysdev.kobj));
                sysfs_remove_link(&mem_blk->sysdev.kobj,
                         kobject_name(&node_devices[nid].sysdev.kobj));
        }
+       NODEMASK_FREE(unlinked_nodes);
        return 0;
 }